Quick Graphics Card OC question...

When someone is saying that they have oc'ed their graphics card, they talk about scoring....i.e. 6000, 6600, etc....
what is this number refering to?
is it the pixel fill rate? or the texel fill rate? what is everyone talking about?
thanks...

Usually someone will state what score they got in a graphics benchmark program, like 3dmark05, 3dmark03, aquamark3, etc. Each program has a different scale of "grading", but it lets everyone compare their numbers and see where they fit in.